Also, the present invention relates to an information medium having management data for sharing objects of a plurality of contents, an apparatus for playing back information recorded on the medium, a method of recording information containing the management data on the medium, and a method of playing back information from the medium on the basis of the management data.
As optical discs that can record video (moving picture) data with high quality and at high density, and can record various kinds of information such as multiangle video data, sub-picture data, multilingual audio data, multichannel audio data, and the like, DVD video discs have been developed, and are beginning to be put into the market (DVD is an abbreviation for a digital versatile disc).
The DVD video disc standards can support compressed multichannel audio (AC-3, MPEG, and the like) and non-compressed linear PCM (from a sampling rate of 48 kHz/16 quantization bits to a sampling rate of 96 kHz/24 quantization bits). Linear PCM of DVD video has high-sound quality specifications with high sampling rate and high quantization bits superior to conventional music CDs (a sampling rate of 44.1 kHz/16 quantization bits). Especially, linear PCM having a sampling rate of 96 kHz/20 to 24 quantization bits qualifies for the next generation digital audio discs (so-called super CDs or super audio discs).
However, DVD video specifications give priority to video over audio, and audio priority specifications superior to audio specifications of DVD video in terms of not only the sampling frequency and the number of quantization bits but also the number of recordable channels, recordable time, and the like, are yet to come.
To meet such demand, DVD audio specifications are being explored (however, the DVD audio specifications are not yet a prior art). The DVD audio specifications can support up to linear PCM having a sampling rate of 192 kHz and 24 quantization bits as well as linear PCM having a sampling rate of 48 kHz to 96 kHz and 16 to 24 quantization bits. In the future version up of DVD audio specifications, higher-sound quality specifications may be introduced.
DVD audio can cope with such future scale-up since it can commonly use some specifications of DVD video capable of large-amount recording that includes even digital Hi-Vision video as a target.
Also, DVD audio can take future technical, market, and economic advantages that will become available along with the improvement of DVD video.
For example, when a large-amount DVD disc which will be available in the future in DVD video is used in DVD audio, the sampling frequency, the number of quantization bits, the number of recording channels, and the like used in recording can be increased considerably if the recording time remains the same. The technique of a DVD video recorder which will be put into the market in the near future and uses a DVD-RAM (or rewritable DVD-RW or write-once DVD-R) can be used in a DVD audio recorder that will become available soon.
Furthermore, if the market scale expands as DVD video prevails, media (DVD-ROM discs, DVD-RAM/DVD-RW discs, DVD-R discs, and the like), components (disc drive, optical pickup, various ICs, and the like), various control programs, and the like are standardized, and a cost reduction of DVD audio products having many features and high sound quality is promoted. With the spread of DVD audio, DVD video can also take future technical, market, and economical advantages that will become available along with the improvement of DVD audio.
As a management method for controlling playback of video (moving picture) or audio (music or the like) contents, it is a common practice to manage playback of contents produced according to their purposes. By contrast, with recent diversification of users' requirements, video and music have vague boundary, and requirements for partly using the contents that can be independently played back as video in music or for commonly using contents by allowing video created for music to be played back as video alone are increasing among producers of these contents (contents providers).
The DVD audio specifications according to the present invention can meet such requirements of the contents providers. More specifically, the DVD audio specifications normally give priority to audio over video, but it is possible to build a system compatible with both DVD video and DVD audio. That is, the DVD audio specifications can provide an audio only disc (A disc) including DVD audio contents alone, and an audio+video disc (AV disc) including both audio and video contents. In such case, upon playing back the audio contents of an AV disc, its video contents can also be accessed.
In the DVD audio specifications according to the present invention, not only video picture data as subsets of the DVD video specifications, but also high-resolution still picture data, text information, and menu data (visual menu data that can be freely designed by the contents provider) can be added to audio data with high-sound quality specifications.